408 



SERIAL MICROSCOPIC SECTIONS 



[CH.XI 



(3) Place in the microtome so that the right side of the object 

 meets the edge of the knife first. 



(4) Mount the sections like the words in a printed book. This 

 will bring the first or dorsalmost section in the upper left-hand corner 



Vontalj 



FIG. 240. FRONTAL SERIAL SECTIONS SHOWING THE ARRANGEMENT OF THE 

 EMBRYO IN THE IMBEDDING MASS, THE CONNECTION WITH THE MICROTOME 

 HOLDER, AND THE POSITION OF THE SECTIONS ON THE GLASS SLIDE. 



Microtome Holder The metal disc and stem for holding the imbedded embryo 

 in the microtome while sectioning. 



Imbedded Embryo The embryo in the proper position for frontal sections. 



Frontal Sections A slide showing the proper arrangement of frontal sections. 



i, 2, j, 4 Serial order in which the sections are arranged like the words in a 

 printed book. 



In section / the word dorsal indicates that the section has its dorsal face upward 

 away from the slide while the ventral face is down in contact with the slide. 



In section 3, the words cephalic, caudal, dextral, sinistral are wrong side up so 

 that they will appear erect under the compound microscope. 



of the series. The dorsal face will be up, the right side to the left, 

 and the cephalic end toward the lower edge of the slide (fig. 240-241). 



Pig 



4 



~ieT 





Sea 440 

 ^Ot 453 



19OO 



FIG. 241. FRONTAL SERIAL SECTIONS SHOWING THE ARRANGEMENT AND THE 

 NUMBERS OF THE SECTIONS ON THIS SLIDE. THE SLIDE is PROPERLY LABELED. 



Under the compound microscope the cephalic end will be away from the 

 observer or in front, and the rights and lefts will be as in his own body. 

 If the sections are too long to mount crosswise they can be cut apart 

 and mounted lengthwise of the slide, the order being like that of the 

 words in a line of print as with all serial sections. 



